with several nucleophiles to give multi-substituted cyclobutanes. The reaction of the cyclobutylmagnesium carbenoids with lithium α-sulfonyl carbanions afforded alkylidenecyclobutanes in moderate to good yields. cyclobutane - alkylidenecyclobutane - magnesium carbenoid - cyclobutylmagnesium carbenoid - cyclobutylmagnesium chloride